JP2016147229A - Filter for filtration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter for filtration capable of capturing SS particles in liquid to be filtered by utilizing a mechanism of deep bed filtration and a mechanism of cake filtration, and further keeping a filtration flow rate even after being shifted to the cake filtration.SOLUTION: A filter for filtration includes a filter body having a tabular substrate having a plurality of open holes formed thereon, and a plurality of fine structures formed on the primary surface side into which liquid to be filtered flows in the substrate.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a filter for filtration.

In recent years, due to industrial development and population increase, effective use of water resources has been demanded. In order to effectively use water resources, it is important to purify and reuse various wastewaters such as industrial wastewater and domestic wastewater. In order to purify the wastewater, it is necessary to separate and remove water insoluble matters and impurities contained in the water.
Examples of a method for separating and removing water-insoluble matter and impurity particles contained in water include a membrane separation method, a centrifugal separation method, an activated carbon adsorption method, an ozone treatment method, and a method for removing suspended solids by adding a flocculant.

  In a filtration method represented by a membrane separation method, water containing suspended substances (hereinafter sometimes referred to as SS particles) that are substances to be removed is added to filters using various forms of membranes and filter media. The SS particles are separated from the water by passing through. As typical filtration mechanisms, there are mechanisms called surface filtration, depth filtration (depth filtration), and cake filtration.

Surface filtration is a mechanism for receiving SS particles contained in water passing through the filter at the surface of the filter. Surface filtration mainly captures SS particles that are larger than the pores of the filter. For example, in a filtration using a membrane, a surface filtration mechanism is mainly used.
Deep-layer filtration is a mechanism that utilizes adhesion of SS particles not only to the surface of the filter but also to the entire surface of the filter in contact with water containing SS particles, such as the inner surface of the pores. In depth filtration, particles that are mainly smaller than the pores of the filter are trapped. For example, in the filtration using a tower filled with a filtering material such as sand, a mechanism of depth filtration is used.
Cake filtration is a mechanism in which SS particles themselves captured by a filter form a cake and function as a filter. Cake filtration captures SS particles that are even smaller than depth filtration.

  Conventionally, a surface filtration mechanism is mainly used in the filtration that separates SS particles from water using a filter using a wire mesh. In a filter using a wire mesh, if a deep layer filtration mechanism is used, particles smaller than the pores of the filter can be captured, the filter is not easily blocked, and the water flow rate is easily secured. However, in a filter using a wire mesh, it is difficult to secure a contact area between the filter and water containing SS particles, and thus there is a case where the mechanism of the depth filtration cannot be used.

  Generally, when water containing SS particles is passed through a filter to remove SS particles from the water, a cake of SS particles is formed and the process proceeds to cake filtration. The filtration performance at this time depends on the formed cake (in other words, depends on SS particles), and a decrease in the filtration flow rate is observed as the cake thickness increases.

  Further, when the filter is washed, if the filter and the SS particles are not smoothly separated, the washing efficiency is lowered, and there is a concern that the consumption of washing water is increased and the performance of the filter is lowered. In addition, in order to remove fine particles, it is necessary to add a flocculant, and there is a problem that the amount of sludge increases.

JP 2008-180206 A

  The problem to be solved by the present invention is a filter for filtration that can capture SS particles in a liquid to be filtered by using a mechanism of deep layer filtration and a mechanism of cake filtration, and can maintain a filtration flow rate even after shifting to cake filtration. Is to provide.

  The filtration filter according to the embodiment includes a plate-like base material having a plurality of through holes, and a plurality of fine structures formed on the primary surface side into which the liquid to be filtered flows out of the base material. With body.

The schematic block diagram which shows an example of the filtration processing apparatus to which the filter for filtration of embodiment is applied. The external appearance perspective view which shows the filter for filtration of embodiment. Sectional drawing when the filter for filtration is seen from the end surface side. The principal part expansion schematic diagram which shows the base material in which the fine structure was formed. The SEM photograph at the time of making a fine structure into a needle-like structure. The SEM photograph at the time of making a fine structure into a polyhedron structure. The SEM photograph at the time of making a fine structure into a polyhedron structure. The principal part expanded sectional view when the filter for filtration of another embodiment is seen from the end surface side. The top view which shows the filter for filtration of another embodiment. The top view which shows the filter for filtration of another embodiment. The top view which shows the filter for filtration of another embodiment.

Hereinafter, the filter for filtration of an embodiment is explained.
Drawing 1 is a schematic structure figure showing an example of a filtration processing device to which a filter for filtration of an embodiment is applied.
The filtration apparatus 100 includes a liquid tank 101 for storing a liquid to be filtered, the filter 10 for filtration according to the embodiment, a treatment liquid tank 103, and a concentrated sludge tank 104. Further, a pump 106 that pumps the liquid to be filtered in the liquid tank 101 to be filtered to the filter 10 for filtration, a pump 107 that discharges the treated water (filtered liquid) in the liquid tank 103 or returns it to the filter 10 for filtration, And a plurality of pipes 108 connecting them.

  The to-be-filtrated tank 101 stores the to-be-filtrated liquid. Examples of the liquid to be filtered include water containing SS particles. The to-be-filtrated liquid tank 101 may be provided with a stirrer for stirring the inside of the to-be-filtrated liquid tank 101. The shape, volume, material, and the like of the liquid tank 101 to be filtered can be appropriately determined according to the use of the filtration apparatus 100, and are not particularly limited.

  The filter 10 for filtration removes filtration target objects, such as SS particle | grains, from a to-be-filtered liquid, and produces | generates treated water (filtered liquid). The detailed configuration of the filter 10 for filtration will be described later.

  The processing liquid tank 103 stores the processing liquid. The treatment liquid is generated by passing the liquid to be filtered through the filter 10 for filtration. The shape, capacity, material, and the like of the processing liquid tank 103 can be appropriately determined according to the use of the filtration processing apparatus 100, and are not particularly limited.

  The concentrated sludge tank 104 stores a concentrated liquid containing a lot of SS particles removed from the liquid to be filtered. The concentrated liquid is a processing liquid after being used for washing the filter 10 for filtration. The shape, capacity, material, and the like of the concentrated sludge tank 104 can be appropriately determined according to the use of the filtration apparatus 100, and are not particularly limited.

FIG. 2 is an external perspective view showing the filter for filtration according to the embodiment. FIG. 3 is a cross-sectional view when the filter for filtration is viewed from the end surface side.
The filter 10 for filtration has a plate-like base material 11 formed with a plurality of through holes 13 penetrating in the thickness direction, and at least a primary surface (inflow surface) through which the liquid to be filtered flows. ) It is composed of a plurality of fine structures 5 formed on the 11a side and a filter body 12 provided. In the present embodiment, the fine structure 5 is formed so as to cover the primary surface (inflow surface) 11 a, the secondary surface (outflow surface) 11 b through which the liquid to be filtered flows, and the inner wall surface of the through hole 13.

  The substrate 11 is made of, for example, a metal plate. Specifically, a SUS plate, an aluminum plate, an aluminum alloy plate, a copper plate, a copper alloy plate, a zinc plate, or the like can be used. As the shape of the base material 11, a plate material having an arbitrary shape such as a rectangular plate shape, a disk shape, an elliptical plate shape, or a polygonal plate shape can be used. In this embodiment, a rectangular metal plate is used.

  The through holes 13, 13... Are cylindrical holes that connect the primary surface (inflow surface) 11a and the secondary surface (outflow surface) 11b of the base material 11. Each through-hole 13 is a hole having a diameter different between the primary surface 11a side and the secondary surface 11b side even if the diameter is uniform from the primary surface 11a side to the secondary surface 11b side. Also good.

  In the present embodiment, the through hole 13 has a circular planar shape along the primary surface 11a. And many such through-holes 13, 13, ... are formed so that it may become a staggered arrangement | sequence along the primary surface 11a.

  The filtration filter 10 having such a configuration allows the liquid to be filtered to flow from the primary surface (inflow surface) 11a side, passes through the through-hole 13, and filters the liquid to be filtered, and from the secondary surface (outflow surface) 11b. The treated water after filtration is discharged.

  The fine structure 5 has, for example, at least one of a truncated cone shape, an elliptical cone shape, a polygonal pyramid shape, a truncated cone shape, an elliptical truncated cone shape, and a polygonal truncated cone shape. The microstructure 5 according to the embodiment is a needle-like structure that is tapered from the proximal end toward the distal end.

FIG. 4 is an enlarged schematic view of a main part showing a base material on which a fine structure is formed.
The fine structure 5 is composed of a plating layer 3 formed on the base 11 by, for example, electroplating. In addition, it is preferable that an underlayer 4 that further improves the adhesion between the plating layer 3 and the base material 11 is further formed between the plating layer 3 and the base material 11 constituting the microstructure 5.

  As the base material 11 that forms the fine structure 5, a material that can be used in a liquid to be filtered that is filtered using the filter 10 for filtration is used. The material of the base material 11 is preferably a metal so that the plating layer 3 or the plating layer 3 and the base layer 4 can be easily formed by using a plating process. As the metal used for the substrate 11, for example, iron, nickel, copper, and alloys thereof are preferably used. Among them, it is particularly preferable to use a stainless steel plate as the base material 11 that is excellent in corrosion resistance, low cost, and easy to process.

  The underlayer 4 is provided as necessary in order to improve the adhesion of the plating layer 3 to the base material 11. As a material used for the underlayer 4, for example, when the plating layer 3 made of a nickel alloy is formed on the surface of the substrate 11, it is preferable to use nickel or a nickel alloy. Examples of the nickel alloy include those containing one or more elements selected from boron, phosphorus, and zinc.

  The thickness of the foundation layer 4 is set to be equal to or greater than the thickness that can improve the adhesion of the plating layer 3 to the substrate 11. In addition, the thickness of the base layer 4 is set to a thickness in which the diameter of the through-hole 13 is in a range suitable for passing a liquid to be filtered containing SS particles through the filter 10 for filtration.

  The plating layer 3 in the embodiment is a composite body in which a plurality of fine structures (in the present embodiment, needle-like structures) 5 are gathered on the surface of the base layer 4. In each microstructure 5, a base 5 a that is a region closer to the base material 11 than the base end 53 a of the microstructure 5 is integrated with a base 5 a of another adjacent microstructure 5. As a result, the base 5 a of the fine structure 5 is continuously formed on the surface of the underlayer 4.

The fine structure 5 in the present embodiment has, for example, a truncated cone shape, an elliptical cone shape, a polygonal pyramid shape, a truncated cone shape, an elliptical truncated cone shape, and a polygonal truncated cone shape. Each microstructure 5 having such a cone shape or frustum shape has a tapered shape from the base end 53 a toward the tip 52.
FIG. 5 shows an SEM photograph (secondary electron image (SEI), 15.0 kV, 20000 times) when the microstructure 5 is a needle-like structure.

  Between the fine structures 5 made into the needle-like structures, troughs 53 are formed that become narrower as they approach the base end 53a in a cross-sectional view. The valley 53 is formed so as to surround each microstructure 5 in plan view. The valleys 53 that surround each microstructure 5 are formed so as to be connected to the valley 53 that surrounds another adjacent microstructure 5 in a plan view.

In the filter 10 for filtration shown in FIG. 4, SS particles captured from the liquid to be filtered are attached to some of the fine structures 5.
The number of the fine structures 5 per unit area (1 μm ² ) of the base material 11 is 1.2 to 10.0 / μm ² . If the number of the fine structures 5 per unit area (1 μm ² ) is less than the above range, the contact area between the filter 10 for filtration and the liquid to be filtered containing SS particles is insufficient, and the effect of the mechanism of depth filtration is obtained. Since it becomes insufficient, it becomes difficult to capture SS particles in the liquid to be filtered.

Further, when the number of the fine structures 5 per unit area (1 μm ² ) is less than the above range, the SS particles are hardly captured by the fine structures 5, so that the cake 7 is hardly formed. However, when the number of the fine structures 5 per unit area (1 μm ² ) exceeds the above range, the SS particles are hardly removed from the fine structures 5 even if the washing is performed, and the detergency becomes insufficient.

When the number of the fine structures 5 per unit area is 1.2 pieces / μm ² or more, the surface area of the filter 10 for filtration becomes sufficiently large, and the SS particles are easily caught between the adjacent fine structures 5. For this reason, it can be set as the filter 10 for filtration in which SS particle | grains are easy to be capture | acquired by the mechanism of deep layer filtration, and the cake 7 is easy to be formed with the capture | acquired SS particle | grains.

Therefore, the filter 10 for filtration has the outstanding removal function which can capture | acquire SS particle | grains using the mechanism of depth filtration and the mechanism of cake filtration. The number of the fine structures 5 per unit area is preferably 3.0 / μm ² or more in order to obtain a filter 10 having a higher SS particle removal function.

When the number of the fine structures 5 per unit area is 10.0 pieces / μm ² or less, the space between the adjacent fine structures 5 is prevented from becoming too narrow. For this reason, as shown in FIG. 4, a sufficiently wide space 31 surrounded by the valleys 53 formed between the adjacent microstructures 5 and the cake 7 formed on the plating layer 3 is formed. It is formed. The space 31 functions as a flow path through which the cake-filtered treated water flows when the cake 7 is formed.

For this reason, compared with the filter which does not have the fine structure 5, since the area where the process liquid which passed the cake 7 is obtained becomes large, the filtration flow rate can be enlarged. Therefore, the filter 10 for filtration is easy to remove SS particles and has a large filtration flow rate. The number of the fine structures 5 per unit area is preferably 7.0 pieces / μm ² or less in order to obtain an excellent filter 10 for filtration having a larger filtration flow rate.

The number of the fine structures 5 per unit area (1 μm ² ) of the base material 11 is measured by the following method.
The filter for filtration is observed with an electron microscope, and the number of apexes of the needle-like structure existing in a square having a length of 2 μm, a width of 2 μm, and an area of 4 μm ² is measured at four points. Then, the number of apexes of the needle-like structures measured at four locations is averaged, and the number of needle-like structures per unit area (1 μm ² ) is calculated.

  The number of the fine structures 5 per unit length (1 μm) in the cross section of the substrate 11 is 1.0 to 4.0 pieces / μm. When the number of the fine structures 5 per unit length (1 μm) is less than the above range, the contact area between the filter for filtration 10 and the liquid to be filtered containing SS particles is insufficient, and the depth filtration mechanism Since the effect becomes insufficient, it becomes difficult to capture SS particles in the liquid to be filtered.

  On the other hand, when the number of the fine structures 5 per unit length (1 μm) exceeds the above range, the valleys 53 formed between the adjacent fine structures 5 and the cake formed on the plating layer 3 are formed. Since the space 31 surrounded by 7 becomes narrow, the filtration flow rate may decrease.

When the number of the fine structures 5 per unit length is 1.0 / μm or more, as in the case where the number of the fine structures 5 per unit area is 1.2 / μm ² or more. In addition, it has an excellent removal function capable of capturing SS particles by using a mechanism of deep layer filtration and a mechanism of cake filtration. The number of the fine structures 5 per unit length is preferably 1.5 / μm or more in order to obtain a filter 10 having a higher SS particle removing function.

When the number of the fine structures 5 per unit length is 4.0 pieces / μm or less, similarly to the case where the number of the fine structures 5 per unit area is 10.0 pieces / μm ² or less. The space between the adjacent fine structures 5 is prevented from becoming too narrow. For this reason, a sufficiently wide space 31 surrounded by the valleys 53 formed between the adjacent microstructures 5 and the cake 7 formed on the plating layer 3 is formed, and the filtration is performed. It can be set as the filter 10 for filtration with a big flow volume. The number of the fine structures 5 per unit length is preferably 3.0 pieces / μm or less in order to obtain the filter 10 for filtration having a larger filtration flow rate.

The number of the fine structures 5 per unit length (1 μm) in the cross section of the substrate 11 is measured by the following method.
The filter 10 for filtration is fixed by embedding resin and cut, and the cut surface is smoothed by ion milling and photographed using a scanning electron microscope (SEM). Thereafter, the number of needle-like microstructures per 10 μm is measured along the substantially extending direction of the surface of the filter base material in the photograph of the photographed cross section of the filter base material. Then, the number of fine structures per unit length (1 μm) is calculated from the measured number of fine structures 5.

  In the present embodiment, the average height H and the average width D of the base end portion of the needle-like microstructure 5 in the cross section of the base material 11 are those obtained by measuring the dimensions of the following portions by the measurement method shown below. It is. As shown in FIG. 4, valleys 53 are formed between adjacent fine structures 5 in the cross section of the base material 11. In the cross section of the base material 11, the base ends 53 a and 53 a that are the valley bottoms facing each other with the fine structure 5 interposed therebetween are connected by a straight line 51, and the length thereof is set to the width D 1 and D 2 of the base end portion of the fine structure 5. To do. The shortest distance between the tip 52 of the fine structure 5 and the straight line 51 is defined as the heights H1 and H2 of the fine structure 5.

  When the two fine structures 57 and 58 are integrated in the cross section of the base material 11 (the fine structure indicated by reference numeral 59 in FIG. 4), the dimensions of the following portions are set to the fine structures 57 and 58, respectively. The heights H3 and H4 of 58 and the widths D3 and D4 of the base ends of the fine structures 57 and 58 were used.

  First, the straight ends 54 connect the base ends 53a and 53a, which are the valley bottoms facing each other across the fine structure 59 in which the needle-like fine structures 57 and 58 are integrated. Next, a perpendicular line 56 is drawn from the bottom of the valley 55 between the two microstructures 57 and 58 toward the straight line 54. The distances from the intersection of the perpendicular 56 and the straight line 54 to the base ends 53a and 53a are defined as the widths D3 and D4 of the base ends of the fine structures 57 and 58, respectively.

  Further, the shortest distances between the tips 52a and 52b of the fine structures 57 and 58 and the straight line 54 are defined as heights H3 and H4 of the fine structures 57 and 58, respectively. In addition, when the length of the perpendicular 56 is less than 3/4 of both the heights H3 and H4 of the fine structures 57 and 58, it is regarded as two independent fine structures. Further, the criterion that the two fine structures 57 and 58 are integrated is a case other than the case where the two fine structures are regarded as independent.

  In order to measure the height of the needle-like fine structure 5 and the width of the base end portion of the fine structure 5, the filter 10 for filtration is fixed by embedding resin and cut, and the cut surface is polished by ion milling. Then, the image is taken using a scanning electron microscope (SEM). Thereafter, a range of 10 μm in length along the substantially extending direction of the surface of the base material in an enlarged photograph of the cross section of the base material 11 taken as one measurement region, and all the above-described fine structures existing in the four measurement regions The height of the object 5 and the width of the base end are measured. The average value of the heights of the four fine structures 5 measured is defined as the average height H of the fine structures 5. Moreover, let the average value of the width | variety of the base end part of the four fine structures 5 measured be the average width D of the base end part of the fine structure 5. FIG.

  The coefficient of variation of the height of the needle-like microstructure 5 in the cross section of the substrate 11 is preferably 0.15 to 0.50. The coefficient of variation is obtained by dividing the standard deviation of the height distribution of the fine structures 5 in the cross section of the base material 11 by the arithmetic average value of the heights of the fine structures 5.

  When the coefficient of variation is in the range of 0.15 to 0.50, the filter 10 for filtration is further excellent in the function of removing SS particles and the detergency. When the variation coefficient is less than 0.15, the flow of the liquid to be filtered containing SS particles on the surface of the filter 10 for filtration is monotonous when the liquid to be filtered containing SS particles is passed through the filter 10 for filtration. Thus, the SS particles are hardly captured by the fine structure 5. Moreover, when the above coefficient of variation exceeds 0.50, it becomes difficult to obtain a function of supporting the cake 7 formed on the surface of the plating layer 3 by the fine structure 5 having a low height.

  When the variation coefficient is 0.15 or more, the height variation of the fine structure 5 is sufficiently large. For this reason, when passing the liquid to be filtered containing SS particles through the filter 10 for filtration, the flow of the liquid to be filtered containing SS particles on the surface of the filter 10 for filtration becomes complicated, and the fine structure with a high height. SS particles are easily caught on the object 5. As a result, the SS particles are easily captured by the deep layer filtration mechanism, and the cake 7 is easily formed on the surface of the plating layer 3 starting from the SS particles caught on the fine structure 5 having a high height. The coefficient of variation is preferably 0.18 or more in order to obtain a filter 10 for filtration in which SS particles are more easily captured.

  If the coefficient of variation is 0.50 or less, the cake 7 formed on the surface of the plating layer 3 is supported by the microstructure 5 having a low height, and thus formed between the adjacent microstructures 5. The space 31 surrounded by the valley 53 and the cake 7 is easily secured. For this reason, after the cake 7 is formed by filtration, the treatment liquid subjected to cake filtration easily flows in the space 31, and the filtration flow rate increases. Therefore, the filter 10 for filtration becomes a thing excellent in the filtration flow volume compared with the filter without a needle-like structure. The coefficient of variation is preferably 0.36 or less in order to obtain a filter 10 having a higher filtration flow rate.

  The aspect ratio H / D between the average width D and the average height H of the base end portion of the needle-like microstructure 5 in the cross section of the base material 11 is preferably 0.5 to 4.0. When the aspect ratio H / D is 0.5 or more, sufficient is surrounded by the valleys 53 formed between the adjacent needle-like microstructures 5 and the cake 7 formed on the plating layer 3. A space 31 having a height is formed.

  For this reason, after the cake 7 is formed by filtration, the treated water subjected to the cake filtration easily flows in the space 31, and the filtration flow rate is excellent. The aspect ratio H / D is preferably 1.0 or more in order to obtain a filter 10 having a higher filtration flow rate. When the aspect ratio H / D is 4.0 or less, the microstructure 5 is excellent in strength, and thus the filter 10 for filtration is excellent in durability. The aspect ratio H / D is preferably 3.0 or less in order to obtain a filter 10 having a further excellent durability.

  The average height H of the needle-like microstructure 5 in the cross section of the substrate 11 is preferably 0.2 to 2.5 μm. When the average height H of the fine structure 5 is 0.2 μm or more, the fine structure 5 is surrounded by the valleys 53 formed between the adjacent fine structures 5 and the cake 7 formed on the plating layer 3. A sufficiently high space 31 is formed. For this reason, after the cake is formed at the time of filtration, the cake-filtered processing liquid easily flows in the space 31, and the filtration flow rate is excellent.

The average height H of the fine structure 5 is preferably 0.4 μm or more in order to obtain a filter 10 having a further excellent filtration flow rate. When the average height H of the needle-like microstructure 5 is 2.5 μm or less, the space between the adjacent microstructures 5 is prevented from becoming too narrow. For this reason, it becomes the filter 10 for filtration excellent in the filtration flow volume by which the space 31 was fully ensured similarly to the case where it is 10.0 piece / micrometer < ² > or less. The average height H of the fine structure 5 is preferably 1.8 μm or less in order to obtain a filter 10 having a further excellent filtration flow rate.

The relationship between the average width D of the base end portion of the needle-like microstructure 5 in the cross section of the base material 11 and the average particle diameter (D ₅₀ ) φ (average particle size of SS particles) of the removal target substance is φ / It is preferable to satisfy D ≧ 0.33. When φ / D is 0.33 or more, SS particles are less likely to enter the vicinity of the valley bottom of the valley 53 formed between the adjacent microstructures 5. Therefore, a wide space 31 surrounded by the valleys 53 and the cake 7 formed on the plating layer 3 is easily formed. Therefore, the filter 10 for filtration is easy to flow the cake-filtered processing liquid in the space 31 and has an excellent filtration flow rate.

  The φ / D is preferably 0.50 or more in order to obtain a filter 10 having a higher filtration flow rate. The φ / D is preferably 3.00 or less. When the φ / D is 3.00 or less, the SS particles are more easily caught between the adjacent microstructures 5.

For this reason, it becomes the filter 10 for filtration which SS particle | grains are easy to be further capture | acquired by the mechanism of deep layer filtration, and the cake 7 is easy to be formed with the capture | acquired SS particle | grain. The φ / D is more preferably 2.00 or less in order to obtain the filter 10 for filtration in which SS particles are more easily captured.
Here, the average particle diameter φ is measured by a laser diffraction method. Specifically, it can be measured by a SALD-DS21 type measuring device (trade name) manufactured by Shimadzu Corporation.

  As a metal used for the plating layer 3 formed of the plurality of fine structures 5, a metal capable of depositing the plurality of fine structures 5 on the surface of the substrate 11 or the base layer 4 by a process such as electroplating is used. Examples of such a metal include iron, nickel, copper, and alloys thereof. As the metal used for the plating layer 3, nickel or a nickel alloy is preferably used because it is a metal that can easily control the shape of the microstructure 5 and has excellent corrosion resistance. Examples of the nickel alloy include those containing one or more elements selected from boron, phosphorus, and zinc.

  When the primary surface 11a side in the filter body 12 constituting the filter for filtration 10 is viewed in plan, the opening ratio, which is the ratio of the total area of the opening surface of the through hole 13 to the flat area of the entire primary surface 11a, is 0.05. % Or more and preferably 30% or less. Further, the diameter of each through-hole 13 (when the cross-sectional shape of the through-hole is circular) or the diameter of the inscribed circle (when the cross-sectional shape of the through-hole is polygonal) is 1 μm or more and 5 mm or less. preferable.

  When the fine structure 5 is formed into a conical shape or a frustum shape, for example, a needle-shaped structure, if the opening ratio G is less than 0.05%, the amount of filtered treated water passing through is too small, which is efficient. It becomes difficult to filter the liquid to be filtered. By maintaining the aperture ratio G at 0.05% or more, the amount of treated water passing through can be maintained appropriately, and the filtrate to be filtered can be efficiently filtered. On the other hand, when the aperture ratio G exceeds 30%, it is difficult to form a bridge due to the captured SS, and there is a concern that the filtration performance by cake filtration is lowered. By maintaining the aperture ratio G at 30% or less, the filtration performance by cake filtration can be enhanced.

In the above-described embodiment, the example in which the fine structure 5 is a cone shape or a frustum shape, for example, a needle-like structure has been described. However, it is also preferable that the fine structure 5 is formed in a polyhedral shape.
6 and 7 are SEM photographs (secondary electron image (SEI), 15.0 kV, 2000 times (FIG. 6), and 5000 times (FIG. 7)) when the fine structure 5 is a polyhedral structure. Show.
When the fine structure 5 is a polyhedral structure, a plurality of polyhedrons are bonded to each other and share a part of the volume. Each of the polyhedral fine structures 5 has a plurality of vertices where three or more planes intersect. Each microstructure 5 has a different shape and a different size, as shown in FIGS. 6 and 7, and the base material 11 or the base layer 4 formed on the base material 11 (see FIG. 4). It is densely formed on the surface. As a result, the portion corresponding to the side of the polyhedron shape faces an irregular direction.

  The average value of the maximum outer dimensions of the polyhedral fine structure 5 is preferably 0.5 to 10 μm. When the average maximum outer dimension of the precipitate is within the above range, the SS particles in the liquid to be filtered are easily caught.

  In particular, when the average particle diameter of the SS particles in the liquid to be filtered is 0.1 to 10 μm, the SS particles are easily caught on the plating layer 3. Therefore, when the average particle diameter of the SS particles in the liquid to be filtered is within the above range, the SS particles can be efficiently captured by the mechanism of the depth filtration. Further, when the average maximum outer dimension of the precipitate is within the above range, SS particles are easily caught on the plating layer 3, so that cake is easily formed by the SS particles captured by the filter 10 for filtration. As a result, it becomes easy to capture the SS particles using the cake filtration mechanism, and the filter 10 for filtration having a high function of removing the SS particles is obtained.

  When the average maximum outer dimension of the polyhedral fine structure 5 is less than 0.5 μm, the unevenness of the surface of the plating layer 3 is reduced, and the amount of liquid to be filtered passing through the gaps between the polyhedral precipitates is reduced. As a result, adhesion of SS particles to the plating layer 3 is less likely to occur. The average maximum outer dimension of the polyhedral fine structure 5 is more preferably 2 μm or more. Further, when the average maximum outer dimension of the polyhedral fine structure 5 exceeds 10 μm, the contact area between the plating layer 3 and the liquid to be filtered containing SS particles decreases, and adhesion of SS particles to the plating layer 3 occurs. Less likely to occur. The average maximum external dimension of the polyhedral fine structure 5 is more preferably 8 μm or less.

  The coefficient of variation of the average maximum outer dimension of the polyhedral microstructure 5 is preferably 0.15 to 0.50. When the coefficient of variation is in the range of 0.15 to 0.50, the filter 10 for filtration is further excellent in the function of removing SS particles and the detergency. When the variation coefficient is less than 0.15, the flow of the liquid to be filtered containing SS particles on the surface of the filter 10 for filtration is monotonous when the liquid to be filtered containing SS particles is passed through the filter 10 for filtration. Thus, the SS particles are hardly captured by the fine structure 5. Moreover, when the above coefficient of variation exceeds 0.50, it becomes difficult to obtain a function of supporting the cake 7 formed on the surface of the plating layer 3 by the fine structure 5 having a low height.

  When the variation coefficient is 0.15 or more, the height variation of the fine structure 5 is sufficiently large. For this reason, when passing the liquid to be filtered containing SS particles through the filter 10 for filtration, the flow of the liquid to be filtered containing SS particles on the surface of the filter 10 for filtration becomes complicated, and the fine structure with a high height. SS particles are easily caught on the object 5. As a result, the SS particles are easily captured by the deep layer filtration mechanism, and the cake 7 is easily formed on the surface of the plating layer 3 starting from the SS particles caught on the fine structure 5 having a high height. The coefficient of variation is preferably 0.18 or more in order to obtain a filter 10 for filtration in which SS particles are more easily captured.

  If the coefficient of variation is 0.50 or less, the cake 7 formed on the surface of the plating layer 3 is supported by the microstructure 5 having a low height, and thus formed between the adjacent microstructures 5. The space 31 surrounded by the valley 53 and the cake 7 is easily secured. For this reason, after the cake 7 is formed by filtration, the treatment liquid subjected to cake filtration easily flows in the space 31, and the filtration flow rate increases. Therefore, the filter 10 for filtration becomes a thing excellent in the filtration flow volume compared with the filter without a polyhedron structure. The coefficient of variation is preferably 0.36 or less in order to obtain a filter 10 having a higher filtration flow rate.

The average maximum outer dimension of the polyhedral fine structure 5 is measured by the following measuring method.
That is, an enlarged photograph of the filter for filtration 10 is taken using a scanning electron microscope (SEM), and image processing is performed. Specifically, the outer dimensions of the largest portion of the polyhedral fine structure 5 are measured by selecting ten representative locations for one photograph, and the average value is the average maximum outer shape. Defined as a dimension.

  As the metal used for the plating layer 3, a metal that can obtain a plurality of polyhedral fine structures 5 on the surface of the filter substrate by plating is used. Examples of such a metal include iron, nickel, copper, and alloys thereof. As the metal used for the plating layer 3, nickel or a nickel alloy is preferably used because it is a metal whose shape is easily controlled and excellent in corrosion resistance among the above metals. Examples of the nickel alloy include those containing one or more elements selected from boron, phosphorus, and zinc.

The operation of the filtration apparatus to which the filtration filter according to the embodiment described in detail above is applied will be described.
For example, when the filtered liquid containing SS particles is filtered to obtain treated water using the filtration apparatus 100, first, the filtered liquid stored in the filtered liquid tank 101 is filtered by the pump 106. Pump toward the filter 10.

  In the liquid to be filtered that has flowed into the filtration filter 10, SS particles are captured by the plating layer 3 made up of a number of fine structures 5 formed on the primary surface 11 a of the flat filter 10. Since the filter for filtration 10 has a plurality of fine structures 5 at a predetermined density, the contact area between the filter for filtration 10 and the liquid to be filtered containing SS particles is large. For this reason, agglomerates of SS particles are rapidly formed at a plurality of locations on the surface of the plating layer 3 starting from the SS particles adhering to the surface of the fine structure 5 by the surface filtration and depth filtration mechanisms.

  The formed aggregate grows and peels by continuing the passage of the liquid to be filtered containing SS particles to the filter 10 for filtration, and moves toward the through-hole 13 together with the liquid to be filtered containing SS particles. . The one or more aggregates that have moved to the through-hole 13 become a bridge-like cake 7 that blocks the through-hole 13. Thus, in the processing method of this embodiment, not only the surface filtration mechanism but also the depth filtration mechanism and the cake filtration mechanism can be used to remove small SS particles in the liquid to be filtered. Therefore, excellent filtration performance can be obtained.

  As shown in FIG. 4, the filter 10 for filtration has a valley 53 between adjacent microstructures 5. The valley 53 becomes narrower as it approaches the base end 53a that is the bottom of the valley in a cross-sectional view. For this reason, the SS particles captured by the filtration filter 10 are unlikely to enter the vicinity of the base end 53 a of the valley 53.

  Therefore, in the filter 10 for filtration in which the cake 7 is formed on the surface of the plating layer 3, a sufficiently large space 31 surrounded by the valleys 53 and the cake 7 is formed as shown in FIG. After the space 31 is formed, the upper portion of the space 31 is covered with the lid formed by the cake 7 even if the liquid to be filtered containing SS particles is further passed to the filter 10 for filtration. Therefore, SS particles are difficult to enter the space 31. Therefore, if the liquid to be filtered containing SS particles is continuously passed to the filter 10 for filtration, further SS particles are deposited on the cake 7.

  With the plating layer 3 composed of such a large number of fine structures 5, the SS particles can be efficiently and reliably captured and removed from the liquid to be filtered containing the SS particles. Then, the treated water from which the SS particles have been removed passes through the through-hole 13 formed in the base material 11 and is discharged from the secondary surface 11b of the filtration filter 10 to the treatment liquid tank 103.

  Thus, according to the filter for filtration 10 of the embodiment, by forming a large number of fine structures 5 such as needles or polyhedrons on the primary surface 11a side into which the liquid to be filtered flows, the object to be filtered containing SS particles is formed. It becomes possible to capture and remove SS particles from the liquid efficiently and reliably.

  Further, as in the embodiment, by making the primary surface 11a into which the filtrate to be filtered flows into a flat surface in a large number of fine structures 5, the fluid pressure at the time of the filtrate to be filtered does not concentrate locally. Applied uniformly. Thereby, the durability of the filter body 12 against the hydraulic pressure is enhanced. Further, since the hydraulic pressure does not concentrate locally, damage and isolation of the fine structure 5 can be prevented, and the bridge-shaped cake 7 can be effectively formed.

  In addition, when a large amount of cake accumulates inside the filter 10 for filtration and the amount of water flow decreases, reverse cleaning is performed in which water flows from the secondary surface 11b side of the filter 10 toward the primary surface 11a. Is preferred. The cake discharged by such back washing is collected in the concentrated sludge tank 104 as sludge. The cleaning water used for the reverse cleaning may be sent back to the secondary surface 11b side of the filtration filter 10 by the pump 107 using a part of the processing water stored in the processing liquid tank 103, for example.

  The backwashing of the filtration filter 10 is preferably performed at a stage where the filtration filter 10 has captured a certain amount of SS particles. The timing for performing the cleaning is not particularly limited, and can be appropriately determined according to the amount of SS particles contained in the liquid to be filtered that is allowed to pass through the filter 10 for filtration. In addition to passing the cleaning liquid in the direction opposite to the direction in which the liquid to be filtered containing SS particles is passed through the filtering filter 10 (back washing), the cleaning liquid is allowed to flow on the surface of the filtering filter 10. It can also be done.

  In this embodiment, when the filter 10 for filtration is backwashed, the cleaning liquid flows into the space 31 from multiple directions through the valleys 53 formed so as to surround each fine structure 5. Accordingly, the cake 7 formed so as to cover at least a part of the upper portion of the valley 53 is pushed up by the cleaning liquid, and the peeling of the cake 7 is promoted. Further, the fine structure 5 of the filter 10 for filtration has a tapered shape from the proximal end 53 a toward the distal end 52.

  For this reason, the cake 7 pushed up by the cleaning liquid is easily peeled off from the filter 10 for filtration. In addition, since the fine structure 5 has a tapered shape, the SS particles attached to the fine structure 5 are not easily caught in the valleys 53 during backwashing, and are easily separated from the fine structure 5. Therefore, by performing backwashing, SS particles deposited on the filter 10 for filtration are quickly removed, and the filter 10 for water filtration is regenerated.

In the embodiment described above, the filtering filter 10 is configured by one filter body 12, but it is also preferable to configure the filtering filter 10 by stacking a plurality of filter bodies 12.
FIG. 8 is an enlarged cross-sectional view of a main part when a filter for filtration according to another embodiment is viewed from the end surface side.
The filter 60 for filtration of the present embodiment is formed by stacking a first filter body 61, a second filter body 71, and a third filter body 81 on top of each other. A plurality of through-holes 63 are formed in the plate-like base material 62 constituting the first filter body 61. A plurality of through-holes 73 are formed in the plate-like base material 72 constituting the second filter body 71. Furthermore, a plurality of through holes 83 are formed in the plate-like base material 82 constituting the third filter body 81.

  In this embodiment, the first filter body 61 side constitutes the primary surface 61a through which the liquid to be filtered flows in, and the third filter body 81 side forms the secondary surface 81a through which the liquid to be filtered flows out. And the base material 61,71,81 which comprises each of these 1st filter body 61, the 2nd filter body 71, and the 3rd filter body 81 has the fine structure 5 formed in the surface. Such a fine structure 5 may be a needle-like fine structure shown in FIG. 5 or a polyhedral fine structure shown in FIGS. 6 and 7.

  In this embodiment, each through-hole 63, through-hole 73, and through-hole 83 are formed so as to be arranged on the same central axis. The opening size of the through hole 83 formed in the filter body 81 disposed on the secondary surface 81a side is smaller than that of the through hole 63 formed in the filter body 61 disposed on the primary surface side. Is formed. That is, the opening size is formed so as to decrease in the order of the through hole 63, the through hole 73, and the through hole 83. In addition, the opening size said here should just be the largest diameter in the planar shape of each through-hole.

  According to the filtration filter 60 having such a configuration, the through hole extending from the primary surface 61a into which the liquid to be filtered flows into the secondary surface 81a is narrowed in a stepwise manner. Thereby, SS particles having a relatively large size are captured by the through-hole 63, and SS particles having a relatively small size are captured by the through-hole 71 and the through-hole 81. Can be changed. As a result, clogging of the through-hole due to the cake can be reduced, and the liquid to be filtered can be more efficiently filtered.

In the above-described embodiment, the through holes formed in the filter filter base material are circular and formed in a staggered arrangement, but the shape of the individual through holes and the arrangement form thereof are not limited. .
For example, in the filter 91 for filtration shown in FIG. 9, the through holes 92 having a rectangular planar shape are uniformly arranged at equal intervals.
Moreover, in the filter 94 for filtration shown in FIG. 10, the through holes 95 having a rectangular planar shape are formed in a staggered arrangement.
Furthermore, in the filter 97 for filtration shown in FIG. 11, the through holes 98 having a hexagonal planar shape are formed in a staggered arrangement.

Other than this, the planar shape of the through-hole formed in the base material can be various shapes such as a polygonal shape such as a triangle and a pentagon, an elliptical shape, and a cross shape, and is not limited.
Further, the arrangement form of the plurality of through holes can be arranged at random in addition to the uniform arrangement and the staggered arrangement, and is not limited.

Next, an example of the manufacturing method of the filter for filtration is demonstrated.
In order to manufacture the filter for filtration shown in FIG. 2 provided with a needle-like microstructure on the base material, first, a plate-like base material 11 is prepared. The base material 11 is preferably a metal so that the plating layer 3 or the plating layer 3 and the base layer 4 can be easily formed by using a plating process (see FIG. 4). As the metal used for the substrate 11, for example, iron, nickel, copper, and alloys thereof are preferably used. Among them, it is particularly preferable to use a stainless steel plate as the base material 11 that is excellent in corrosion resistance, low cost, and easy to process.

  Next, a large number of through holes 13 are formed in the base material 11. The through hole 13 can be formed by, for example, punching with a press or etching.

  Next, the base layer 4 is formed on the surface of the base material 11 on which the plurality of through holes 13 are formed using a plating process. As a plating process for forming the underlayer 4, a conventionally known method can be used. For example, before forming the plating layer 3 made of nickel or nickel alloy, when forming the base layer 4 on the surface of the base material 11 made of stainless steel, using electrolytic nickel plating treatment or electroless nickel plating treatment, It is preferable to form the underlayer 4 made of nickel or a nickel alloy.

  Next, a plurality of fine structures 5 are deposited on the surface of the base material 11 provided with the base layer 4 by electroplating, and the base material 11 is covered with the plating layer 3 (plating step). As the electroplating process for forming the plating layer 3, a conventionally known method can be used. For example, when the underlayer 4 and the plating layer 3 are made of nickel or a nickel alloy, an additive is added to the plating bath after the formation of the underlayer 4 to continuously perform electrolytic nickel plating treatment or electroless nickel plating. It is preferable to form the plating layer 3 using a treatment.

  In the electroplating process for depositing a plurality of microstructures 5, the shape and size of the microstructures 5 can be changed by changing the type, concentration, and plating time of the additive added to the plating bath. Examples of the additive include ethylenediamine dihydrochloride and ethylenediamine (EDA).

After performing the plating process for forming the plating layer 3, heat treatment may be performed as necessary to promote crystallization of the plating layer 3.
Moreover, after performing the plating process for forming the plating layer 3, if necessary, the surface of the plating layer 3 is made of another metal or organic matter in order to improve the durability of the filter for filtration. Another coating layer may be formed.

  In addition, a plurality of types of modified regions having different affinity for the liquid to be filtered can be formed on the surface of the plating layer 3. Specifically, the modification treatment of the plating layer 3 includes a hydrophilic treatment and a hydrophobic treatment. By performing such modification treatment, the flow of the liquid to be filtered on the surface of the plating layer 3 becomes more complicated, and the SS particles can be easily aggregated on the surface of the plating layer 3.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

Example 1
A punching metal (base material) having a through-hole diameter of about 3 μm was prepared. After forming a base layer by performing nickel-phosphorus plating on this substrate, as shown in Non-Patent Document 1, the surface of the needle-like microstructure 5 having a thickness of 3.5 μm is formed by plating in the presence of ethylenediamine dihydrochloride (EDA). The filter 10 for filtration was obtained. At this time, the thickness of the filter 10 for filtration was about 1003.5 μm. The aperture ratio was 8.0%.
(Non-Patent Document 1) Tao Hang, Ming Li, Qin Fei and Dali Mao, Characterization of nickel nanocones routed by electrodeposition without any template, Nanotechnology, 19 (2008) 035201 (5pp)

When the surface layer of the plating layer (fine structure 5) of the obtained filter 10 for filtration was observed by SEM, there were 16 to 19 needle-like structures in the range of 4 μm ² (2 μm × 2 μm) (FIG. 6). reference).
Further, this plated layer was fixed with embedded resin, and then cut and observed for cross section. As a result, the average number of needle-like structures per 10 μm was 20, the average height of needle-like structures was 750 nm, and the coefficient of variation was 0.2. 28. The average width of the needle-like structures was 550 nm, and the aspect ratio (height / width) was 1.36.

  Next, the filtration apparatus 100 shown in FIG. 1 was prepared. When the filtration filter 10 produced as described above was installed, and the slurry containing 100 mg / L of alumina having a particle size of 0.1 μm was filtered at a constant pressure of 0.1 MPa using the filtration filter 10, a transparent filter was obtained. Treated water (filtered water) was obtained and could be filtered. When the filtration filter 10 after filtration was fixed with the embedding resin together with the filtration cake (alumina layer) and the cross section was observed, a gap due to irregularities was observed between the cake layer and the filtration filter 10.

  Next, when cleaning water was sent from the treated water side (secondary surface side) of the filtration filter 10 at a pressure of 0.1 Mpa to clean the cake layer, the cake near the gap was cleanly peeled and surface irregularities were observed. Had been restored. When filtration was performed again with this filter, it was confirmed that the same filtration performance as the first filtration was exhibited.

(Example 2)
As in Example 1, a punching metal (base material) having a through-hole diameter of about 3 μm was prepared. After forming a base layer by performing nickel-phosphorus plating on this base material, as shown in Non-Patent Document 2, 2-butyne-1,4-diol is added as an additive, electroless nickel plating treatment is performed, and the thickness is increased. A filter 10 for filtration was obtained by forming a polyhedral fine structure 5 of 3.5 μm on the surface. The thickness of the base material at this time was 1000 μm, and the plate thickness after plating was 1003.5 μm. The hole area ratio at this time was 8%.
(Non-Patent Document 2) S. Chakraborty, Role of organic additives in nickel plating, Transactions of the Metal Finishers' Association of india, Vol. 12, No. 3-4 (2003)

When the surface layer of the plating layer (fine structure 5) of the obtained filter for filtration 10 was observed with an SEM, the average maximum outer dimension was 4 μm. The filtration filter 10 was installed in the filtration apparatus 100 of FIG. 1 in the same manner as in Example 1. Using this filtration filter 10, a slurry containing 100 mg / L of alumina having a particle size of 0.1 μm was 0.1 MPa. When filtered at a constant pressure with pressure, transparent treated water was obtained, and filtration could be performed. When the filtration filter 10 after filtration and the filter cake (alumina layer) were fixed with an embedding resin and the cross section was observed, a gap due to unevenness was observed between the cake layer and the filter.
Next, backwashing water was sent from the secondary side of the filtration filter by applying a pressure of 0.1 MPa, and the cake layer was backwashed. I was back. When filtration was performed again with this filter, it was confirmed that the same filtration performance as the first filtration was exhibited.

  5 ... Fine structure, 10, 60, 91, 94, 97 ... Filter for filtration, 11 ... Base material, 12, 61, 71, 81 ... Filter body, 13 ... Through-hole.

Claims (16)

  A filter for filtration comprising a filter body having a plate-like base material having a plurality of through-holes and a plurality of fine structures formed on at least a primary surface into which the liquid to be filtered flows out of the base material.   The filter for filtration according to claim 1, wherein the fine structure is also formed on at least an inner surface of the through hole.   When the primary surface side of the filter body is viewed in plan, the aperture ratio, which is the ratio of the area of the through hole to the area of the entire primary surface, is 0.05% or more and 30% or less, The filter for filtration according to claim 1 or 2, wherein the inscribed circle has a diameter of 1 µm or more and 5 mm or less.   The filter for filtration according to any one of claims 1 to 3, wherein the through holes are formed in a staggered arrangement.   The filter body is formed in a plurality of layers, and the filter body disposed on the secondary surface side has a smaller opening size of the through hole than the filter body disposed on the primary surface side. The filter for filtration as described in any one.   The filtration according to any one of claims 1 to 5, wherein the fine structure has at least one of a truncated cone shape, an elliptical cone shape, a polygonal pyramid shape, a truncated cone shape, an elliptical truncated cone shape, and a polygonal truncated cone shape. Filter. The filter for filtration according to claim 6, wherein a formation density of the fine structure is in a range of 1.2 to 10.0 pieces / μm ² .   The filter for filtration according to claim 7, wherein the number of formation per unit length in the cross section of the fine structure is in a range of 1 to 4 pieces / µm.   The filter for filtration according to any one of claims 6 to 8, wherein an average height of the fine structure is in a range of 0.2 to 2.5 µm.   The filter for filtration according to claim 9, wherein a variation coefficient of the height of the fine structure is in a range of 0.15 to 0.50.   The filter for filtration according to any one of claims 6 to 10, wherein the fine structure is a needle-like structure having a tapered shape from a proximal end to a distal end.   The filter for filtration according to any one of claims 1 to 5, wherein the fine structure has a polyhedral shape.   The filter for filtration according to claim 12, wherein an average maximum outer dimension of the fine structure is in a range of 0.5 to 10 µm.   The filter for filtration according to claim 12 or 13, wherein a variation coefficient of an average maximum outer dimension of the fine structure is in a range of 0.15 to 0.50.   The filter for filtration according to any one of claims 1 to 14, wherein the fine structure is formed of a metal or an alloy.   The filter for filtration according to claim 15, wherein the fine structure is formed of nickel or a nickel alloy.